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Comet Hale-Bopp: The Most Widely Observed Comet of the 20th Century


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Myself By T.V. Antony Raj
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Image of comet Hale-BoppC/1995 O1 (Hale-Bopp), taken on 1997 April 04. The field shown is about 6.5° x 6.5°. At full resolution, the stars in the image appear slightly elongated, as the camera tracked the comet during the exposure. (Photo: E. Kolmhofer, H. Raab; Johannes-Kepler-Observatory, Linz, Austria)
Image of comet Hale-Bopp (C/1995 O1), taken on 1997 April 04. The field shown is about 6.5° x 6.5°. At full resolution, the stars in the image appear slightly elongated, as the camera tracked the comet during the exposure. (Photo: E. Kolmhofer, H. Raab; Johannes-Kepler-Observatory, Linz, Austria)

On July 23, 1995, two independent observers Alan Hale and Thomas Bopp in the United States discovered the comet Hale-Bopp. This comet formally designated C/1995 O1 was perhaps the most widely observed comet of the 20th century, the third largest comet in the last 500 years, and one of the brightest seen for many decades. It was visible to the naked eye for a record 18 months. The previous record holder, the Great Comet of 1811, officially designated C/1811 F1, was visible to the naked eye for around 260 days.

Dr. Alan Hale
Dr. Alan Hale

Astronomer Alan Hale was born in 1958 in Tachikawa, Japan, when his father was serving in the United States Air Force. Four months later his father got transferred to Holloman Air Force Base outside Alamogordo, New Mexico. Hale served in the United States Navy from 1976 to 1983. In 1980, he graduated from the U.S. Naval Academy. Next, he joined the Jet Propulsion Laboratory (JPL) and worked as an engineering contractor for the Deep Space Network until 1986. As a contractor, he worked in several projects involving spacecraft, including Voyager 2. After Voyager’s encounter with Uranus, he left JPL. He attended New Mexico State University in Las Cruces. In 1992, he earned his Ph.D. in astronomy.

Hale had spent hundreds of hours searching for comets without success. On July 23, 1995, while tracking known comets from his driveway in New Mexico he chanced on the comet co-named after him just after midnight. The comet with an apparent magnitude of 10.5 was near the globular cluster M70 in the constellation of Sagittarius. He checked and confirmed that there was no other deep-sky object near M70. Next, he consulted a directory of known comets and established that none of them was in that area of the sky he had observed. He then found the object moving relative to the background stars.

As a trained astronomer who had seen about 200 comets, Hale to register his finding sent an email to the Central Bureau for Astronomical Telegrams (CBAT) in Cambridge, Massachusetts, the clearing house for astronomical discoveries operating under the auspices of Commission 6 of the International Astronomical Union (IAU). A few hours later his effort was rewarded. His new comet was officially designated C/1995 O1. His name would also be attached.

But Alan Hale was not the only observer that night.

That very night, about 400 miles (644 kilometers) away, Thomas Bopp was observing star clusters and galaxies through telescopes with friends in the desert outside Phoenix, Arizona.

Thomas Bopp in 1997 (Photo: Ron Baalke)
Thomas Bopp in 1997 (Photo: Ron Baalke)

Amateur astronomer Thomas J. Bopp was born in 1949 in Denver, Colorado. Later he relocated with his family to Youngstown, Ohio, where he graduated from Chaney High School in 1967. He attended Youngstown State University in Youngstown, Ohio, and has lived in Tucson, Arizona since 1980. He is a Life member of the Mahoning Valley Astronomical Society (MVAS).

Bopp was a manager at a construction materials factory. He did not own a telescope. He too noticed some fuzzy object near M70 in the constellation of Sagittarius and pointed it out to his friend Jim Steven who owned the 70 inches telescope of Dubsoniano design he was using.

Bopp had never come across a comet. Jim looked at Bopp and said, “Tom, I think you have a comet.”

He knew he had to contact the Central Bureau for Astronomical Telegrams in Cambridge, but he did not have the address with him. So, he drove back home to get it.

In the wee hours he managed to send a Western Union telegram to the Central Bureau for Astronomical Telegrams in Cambridge where its arrival was greeted with bemusement. Brian Marsden, the leading voice on a committee that has the last say laughed. “Nobody sends telegrams anymore,” he commented. “I mean, by the time that telegram got here, Alan Hale had already e-mailed us three times with updated coördinates.”

However, the following morning, the comet was confirmed as a new entity and designated as C/1995 O1. The discovery was announced in International Astronomical Union circular 6187.

Sometimes weird things happened with when major comets appeared. According to a  report, 39 members of a California cult claimed they were departing on a spaceship that was trailing comet Hale-Bopp and ate their last meal before ritually committing mass suicide. For Thomas Bopp, the comet portended a loss. As comet Hale-Bopp reached its most spectacular point in the sky, his brother and sister-in-law who had been out photographing the comet were killed in a late night car crash. “This has been the best week of my life. And, the worst,” he lamented.

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A Near-earth Object, Asteroid 1998 QE2, Is Now Hurtling Towards Earth


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Myself . By T.V. Antony Raj
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Asteroid 1998 QE2 - 1

A near-earth object labeled Asteroid 1998 QE2, is now hurtling towards earth.

The asteroid about 1.7 miles (2.7 kilometers) or nine Queen Elizabeth 2 ship-lengths in size in length has the physical mass to potentially knockout life on Earth. However, we are safe as it is just flying by.

The orbit of asteroid 1998 QE2

On May 31, 2013, at 20:59 UTC (1:59 p.m. Pacific / 4:59 p.m. Eastern) this asteroid will pass within 3.6 million miles (5.8 million km) of Earth – about 15 times the distance to the Moon. While this may seem a great distance for the layman, in astronomical terms it is a mere stone’s throw away. This is the closest approach the asteroid will make to Earth for at least the next two centuries.

The Massachusetts Institute of Technology Lincoln Near Earth Asteroid Research (LINEAR) program near Socorro, New Mexico, discovered this asteroid on August 19, 1998. It is officially known as Asteroid 1998 QE2. It is not named in honor of Queen Elizabeth II, or after that 12-decked, transatlantic-crossing flagship for the Cunard Line. The name was assigned by the NASA-supported Minor Planet Center in Cambridge, Massachusetts, USA. This institute assigns each newly discovered asteroid a provisional designation starting with the year of first detection, along with an alphanumeric code showing the half-month it was discovered, and the sequence within that half-month.

Though this asteroid is not of much interest to those astronomers and scientists on the lookout for hazardous asteroids, it is of interest to those who dabble in radar astronomy and have a 230-foot (70-meter) or larger radar telescopes at their disposal.

Radar astronomer Lance Benner, the principal investigator for the Goldstone radar observations from NASA’s Jet Propulsion Laboratory in Pasadena, California said: “Asteroid 1998 QE2 will be an outstanding radar imaging target at Goldstone and Arecibo and we expect to obtain a series of high-resolution images that could reveal a wealth of surface features … Whenever an asteroid approaches this closely, it provides an important scientific opportunity to study it in detail to understand its size, shape, rotation, surface features, and what they can tell us about its origin. We will also use new radar measurements of the asteroid’s distance and velocity to improve our calculation of its orbit and compute its motion farther into the future than we could otherwise.”

Asteroid 1998 QE2

Asteroids come in various sizes and shapes: dog bones, bowling pins, spheroids, diamonds, muffins, potatoes, etc. Between May 30 and June 9, radar astronomers using NASA’s 230-foot-wide (70 meter) Deep Space Network antenna at Goldstone, California, and the Arecibo Observatory in Puerto Rico, are planning an extensive campaign of observations. The two telescopes with complementary imaging capabilities will enable astronomers to study 1998 QE2 and what it looks like during its brief flyby.

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The Meteorite Explosion that Shook Chelyabinsk, Russia on February 15, 2013


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Myself By T.V. Antony Raj

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Russian Meteor
A meteor seen flying over Russia on Feb. 15 at 3:20: 26 UTC impacted Chelyabinsk.

A meteor entered the Earth’s atmosphere and disintegrated in the skies over Chelyabinsk, Russia, at 7:20:26 PM PST, or 10:20:26 PM EST on February 14 (3:20:26 UTC on February 15).

At a news conference on Friday, NASA scientists said the object was a “tiny asteroid”. The trajectory of this meteor differed appreciably from the trajectory of the asteroid 2012 DA14, which hours later made its flyby of Earth, making both objects completely unrelated.

The Russian Emergency Ministry described it as a shower of meteorite debris. However, some unconfirmed reports suggested that Russian air defenses shot down a meteorite. NASA asteroid expert Don Yeomans, head of the agency’s Near-Earth Object Program Office, said that the object which exploded was most likely an exploding fireball known as a bolide.

According to the preliminary information that appeared in the media unidentified flying objects exploded over several cities in Russia, and the object at Chelyabinsk measured 49 feet (15 meters) across, weighing 7,000 tons and released 30 kilotons of energy when it exploded, and the blast waves blew out window glass of buildings in Chelyabinsk, sending dozens to hospitals, disrupted mobile services, and reportedly injured more than 1,000 people. Many dashboard videos appeared online, showing huge fireballs flying over buildings and exploding with a strong blast. Some walls of the Chelyabinsk Zinc Factory that produced 160,000 metric tons of refined zinc and alloys last year collapsed with extensive damage to the plant.

Now NASA says information provided by a worldwide network of sensors has allowed scientists to revise their estimates for the size of the object before entering Earth’s atmosphere to 55 feet (17 meters), weighing about 10,000 tons. Bill Cooke, head of the Meteoroid Environment Office at NASA’s Marshall Space Flight Center in Huntsville, Alabama said the energy released during the explosion amounted to 500 kilotons equal to that of an exploding modern nuclear bomb.

Fresh data collected from five more infrasound stations located around the world helped to generate these new estimates. The first infra-sound recording of the event took place in Alaska – over 6,500 kilometers away from Chelyabinsk. Calculations performed by Peter Brown at the University of Western Ontario, Canada, using infrasound data show the time taken by the object from entering the atmosphere to its disintegration in the air took 32.5 seconds.

Paul Chodas of NASA’s Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, California said, “We would expect an event of this magnitude to occur once every 100 years on average ”

The present Russia meteor is the largest reported since 1908, when a meteor hit Tunguska, Siberia.

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Asteroid 2012 DA14 Will Flyby on February 15, 2013


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Myself By T.V. Antony Raj

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Diagram of 2012 DA14 passing the Earth on 15 February 2013
Path of 2012 DA14 passing the Earth on 15 February 2013

The small near-Earth asteroid named 2012 DA14 discovered on February 23, 2012, by the OAM Observatory, La Sagra in Spain with an estimated diameter of about 45 meters (about half the size of a football field) weighing about 130,000 metric tons mass probably made of stone in contrast to metal or ice is now hurtling towards the earth. It will pass within about 3.5 Earth radii of the Earth’s surface inside the geosynchronous satellite ring, located about 35,800 kilometers above the equator.

UPCOMING CLOSE APPROACHES TO EARTH - 2

Tomorrow, February 15, 2013, when it passes within 17,200 miles (28,000 kilometers) of Earth, it will not be visible to the naked eye, but will be within range of small telescopes and solidly mounted binoculars, used by experienced observers who have access to appropriate star charts. Here is a note from NASA about the asteroid’s visibility:

On [February 15, 2013], the asteroid will travel rapidly from the southern evening sky into the northern morning sky with its closest Earth approach occurring about 19:26 UTC when it will achieve a magnitude of less than seven, which is somewhat fainter than naked eye visibility. About 4 minutes after its Earth close approach, there is a good chance it will pass into the Earth’s shadow for about 18 minutes or so before reappearing from the eclipse. When traveling rapidly into the northern morning sky, 2012 DA14 will quickly fade in brightness.

Astronomical observatories with their large telescopes would record images of the asteroid, and some observatories will be broadcasting them live online.

Slooh Space Camera will cover the asteroid’s near-approach on Friday, February 15, Slooh to cover live from the Canary Islands with the broadcast team, with several live shows free to the public starting at 6 p.m. PST / 9 p.m. EST / 02:00 UTC (2/16), accompanied by real-time discussions with Slooh Space Camera’s Paul Cox, astronomer and author Bob Berman, and Prescott Observatory manager Matt Francis. Viewers can watch live on their PC or iOS/Android mobile device.

Clay Center Observatory will be offering real-time high-definition video, from 22:00 UTC (6 p.m. EST) February 15 until 8:00 UTC (4 a.m. EST) on February 16. The video feed can be freely accessed worldwide via Clay Center Observatory’s Ustream channel. The observatory has also set up a countdown clock to show how much time remains until the tracking begins.

Bareket Observatory in Israel will be providing a free live webcast of the close approach of asteroid 2012 DA14 using a remote telescope coupled with a cooled CCD camera on February 15 from 21:00 – 22:30 local time (19:00 – 20:30 UTC, or 2 p.m. – 3:30 p.m. CST).

Virtual Telescope Project, which calls itself “the most active facility in the world in astronomical science and education,” will also be following 2012 DA14 on February 15, 2013.

Will anything happen when asteroid 2012 DA14 comes close to Earth? Nothing. According to Paul Chodas, Jon Giorgini and Don Yeomans of NASA/JPL Near-Earth Object Program Office the asteroid will not impact the Earth on February 15, 2013.

The asteroid will have no effect on the tides. It will not cause volcanoes to erupt. It will not trigger earthquakes and tsunamis. Though the asteroid will just hurtle closely past Earth only 17,000 miles away – within the orbits of geosynchronous satellites, most of us will not see it, and we will not be aware of it at all.

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A Near-Earth Object, Asteroid 2012 DA14 Now Hurtling Towards Earth


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Myself By T.V. Antony Raj
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Comets and asteroids that enter the Earth’s neighborhood nudged by the gravitational attraction of nearby planets are known as near-Earth Objects (NEOs).

One such near-Earth asteroid named 4179 Toutatis formerly known as 1989 AC was discovered by Christian Pollas on January 4, 1989, at Caussols, France. On
December 12, 2012, this asteroid with a shape of a “malformed potato” tumbled through space like a fumbled football, within 4.3 million miles from Earth.

UPCOMING CLOSE APPROACHES TO EARTH - 2

Another near-Earth asteroid discovered on February 23, 2012, by the OAM Observatory, La Sagra in Spain with an estimated diameter of about 45 meters (about half the size of a football field) weighing about 130,000 metric tons mass probably made of stone in contrast to metal or ice is now hurtling towards the earth.

Diagram of 2012 DA14 passing the Earth on 15 February 2013
Diagram of 2012 DA14 passing the Earth on 15 February 2013

On February 15, 2013, this asteroid labeled 2012 DA14 will pass within about 3.5 Earth radii of the Earth’s surface inside the geosynchronous weather and communication satellites ring, approximately 35,800 kilometers above the equator.

Even though asteroids like 2012 DA14 fly past Earth almost every 40 years they impact with our planet only every 1200 years or so. Don Yeomans, Paul Chodas, and Jon Giorgini of NASA/JPL Near-Earth Object Program Office after predicting the asteroid’s path have declared that according to their observations, there is no chance that the asteroid might be on a collision course with the Earth, and it will safely fly past Earth’s outer ring of satellites on February 15.

“Since regular sky surveys began in the 1990s, we’ve never seen an object this big gets so close to Earth,” Don Yeomans said.

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Asteroid 2012 DA14 Will Pass the Earth on February 15, 2013


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Myself By T.V. Antony Raj

.UPCOMING CLOSE APPROACHES TO EARTH

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On February 23, 2012, the OAM Observatory, La Sagra in Spain discovered a near-earth asteroid with an estimated diameter of about 45 meters and about 130,000 metric tons mass hurtling towards the earth. On February 15th, 2013, this asteroid named 2012 DA14 will pass within about 3.5 Earth radii of the Earth’s surface inside the geosynchronous satellite ring, located about 35,800 kilometers above the equator. According to Paul Chodas, Jon Giorgini and Don Yeomans of NASA/JPL Near-Earth Object Program Office the asteroid will not impact the Earth on February 15, 2013.

Diagram of 2012 DA14 passing the Earth on 15 February 2013
Diagram of 2012 DA14 passing the Earth on 15 February 2013. – Author: NASA/JPL Near-Earth Object Program Office.

As per calculations, on February 15, 2013, the distance between the asteroid and the Earth will be 0.09 Lunar Distance (35,000 kilometers; 21,000 miles) and travel rapidly from the southern evening sky into the northern morning sky. Its closest Earth approach to Earth would occur at 19:26 UTC achieving magnitude of less than seven; somewhat fainter than naked-eye visibility. Four minutes later 2012 DA14 after passing into the Earth’s shadow for 18 minutes it will reappear from the eclipse, travel swiftly into the northern morning sky and would disappear.

Note: LD = Lunar Distance = ~384,000 kilometers (238,900 miles) .

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Greenland ice sheet melted at unprecedented rate during July 2012


 US environment correspondent
Tuesday 24 July 2012 17.48 EDT

Scientists at Nasa admitted they thought satellite readings were a mistake after images showed 97% surface melt over four days

The Greenland ice sheet on July 8, left, and four days later on the right. In the image, the areas classified as ‘probable melt’ (light pink) correspond to those sites where at least one satellite detected surface melting. The areas classified as ‘melt’ (dark pink) correspond to sites where two or three satellites detected surface melting. Photograph: Nasa

The Greenland ice sheet melted at a faster rate this month than at any other time in recorded history, with virtually the entire ice sheet showing signs of thaw.

The rapid melting over just four days was captured by three satellites. It has stunned and alarmed scientists, and deepened fears about the pace and future consequences of climate change.

In a statement posted on Nasa’s website on Tuesday, scientists admitted the satellite data was so striking they thought at first there had to be a mistake.

“This was so extraordinary that at first I questioned the result: was this real or was it due to a data error?” Son Nghiem of Nasa’s Jet Propulsion Laboratory in Pasadena said in the release.

He consulted with several colleagues, who confirmed his findings. Dorothy Hall, who studies the surface temperature of Greenland at Nasa’s space flight centre in Greenbelt, Maryland, confirmed that the area experienced unusually high temperatures in mid-July, and that there was widespread melting over the surface of the ice sheet.

Climatologists Thomas Mote, at the University of Georgia, and Marco Tedesco, of the City University of New York, also confirmed the melt recorded by the satellites.

However, scientists were still coming to grips with the shocking images on Tuesday. “I think it’s fair to say that this is unprecedented,” Jay Zwally, a glaciologist at Nasa’s Goddard Space Flight Center, told the Guardian.

The set of images released by Nasa on Tuesday show a rapid thaw between 8 July and 12 July. Within that four-day period, measurements from three satellites showed a swift expansion of the area of melting ice, from about 40% of the ice sheet surface to 97%.

Scientists attributed the sudden melt to a heat dome, or a burst of unusually warm air, which hovered over Greenland from 8 July until 16 July.

Greenland had returned to more typical summer conditions by 21 or 22 July, Mote told the Guardian.

But he said the event, while exceptional, should be viewed alongside other compelling evidence of climate change, including on the ground in Greenland.

“What we are seeing at the highest elevations may be a sort of sign of what is going on across the ice sheet,” he said. “At lower elevations on the ice sheet, we are seeing earlier melting, melting later in the season, and more frequent melting over the last 30 years and that is consistent of what you would expect with a warming climate.”

Zwally, who has made almost yearly trips to the Greenland ice sheet for more than three decades, said he had never seen such a rapid melt.

About half of Greenland’s surface ice sheet melts during a typical summer, but Zwally said he and other scientists had been recording an acceleration of that melting process over the last few decades. This year his team had to rebuild their camp, at Swiss Station, when the snow and ice supports melted.

He said he had never seen such a rapid melt over his three decades of nearly yearly trips to the Greenland ice sheet. He was most surprised to see indications in the images of melting even around the area of Summit Station, which is about two miles above sea level.

It was the second unusual event in Greenland in a matter of days, after an iceberg the size of Manhattan broke off from the Petermann glacier. But the rapid melt was viewed as more serious.

“If you look at the 8 July image that might be the maximum extent of warming you would see in the summer,” Zwally noted. “There have been periods when melting might have occurred at higher elevations briefly – maybe for a day or so – but to have it cover the whole of Greenland like this is unknown, certainly in the time of satellite records.”

Jason Box, a glaciologist at Ohio State University who returned on Tuesday from a research trip to Greenland, had been predicting a big melt year for 2012, because of earlier melt and a decline in summer snow flurries.

He said the heat dome was not necessarily a one-off. “This is now the seventh summer in a row with this pattern of warm air being lifted up onto the ice sheet on the summer months,” he said. “What is surprising is just how persistent this circulation anomaly is. Here it is back again for the seventh year in a row in the summer bringing hot, warm
air onto the ice sheet.”

He also said surfaces at higher elevation, now re-frozen, could be more prone to future melting, because of changes in the structure of the snow crystals. Box expected melting to continue at lower elevations.

About half of Greenland’s surface ice sheet melts during a typical summer, but Zwally said he and other scientists had been recording an acceleration of that melting process over the past few decades. This year his team had to rebuild their camp, at Swiss Station, when the snow and ice supports melted.

Lora Koenig, another Goddard glaciologist, told Nasa similar rapid melting occurs about every 150 years. But she warned there were wide-ranging potential implications from this year’s thaw.

“If we continue to observe melting events like this in upcoming years, it will be worrisome.” she told Nasa.

The most immediate consequences are sea level rise and a further warming of the Arctic. In the centre of Greenland, the ice remains up to 3,000 metres deep. On the edges, however, the ice is much, much thinner and has been melting into the sea.

The melting ice sheet is a significant factor in sea level rise. Scientists attribute about one-fifth of the annual sea level rise, which is about 3mm every year, to the melting of the Greenland ice sheet.

In this instance of this month’s extreme melting, Mote said there was evidence of a heat dome over Greenland: or an unusually strong ridge of warm air.

The dome is believed to have moved over Greenland on 8 July, lingering until 16 July.

Source: guardian.co.uk

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